1. FIELD OF THE INVENTION
The present invention relates to the field of earth boring tools and more particularly to rotating or drag bits incorporating diamond cutting elements.
2. Description of the Prior Art
A number of improved diamond cutting tooth designs for use in rotating or drag bits have been devised by assignee of the present application, Norton Christensen, Inc. of Salt Lake City and sold under the trademark BALLASET. A number of these designs have incorporated synthetic diamond elements which are prismatic triangles and are manufactured by the General Electric Company under the trademark GEOSET. Examples of such tooth designs can be found in U.S. Patents Grappendorf et. al., "Tooth Configuration for Earth Boring Bit", U.S. Pat. No. 4,499,959 (1985); Meskin et. al., "Cutting Tooth and Rotating Bit Having Fully Exposed Polycrystalline Diamond," U.S. Pat. No. 4,529,047 (1985); Grappendorf, "Diamond Cutting Element in a Rotary Bit, " U.S. Pat. No. 4,491,188 (1985); Link, "An Improved Diamond Rotating Bit," U.S. Pat. No. 4,550,790 (1985); and Mengel et. al., "Tooth Design to Avoid Shearing Stresses," U.S. Pat. No. 4,515,226 (1985).
One of the design features addressed by each of the prior art designs has been the means of raising and exposing the diamond above the surface of a drill bit in a manner such that the triangular prismatic diamond element, which may be as small as one or three per carat, will be securely retained on the face of the bit under the tremendous stresses encountered in the drilling operation. It is also recognized that in many applications the more diamond that can be effectively exposed to cutting action, the more efficient and aggressive the cutting will be.
However, the size of thermally stable synthetic diamond is limited with the largest commercially available thermally stable GEOSETS being in the range of one per carat size.
Therefore, what is needed is a method and apparatus whereby the limitations of the size of thermally stable synthetic diamond elements can be overcome.